The dental restoration of a partially or wholly edentulous patient with an artificial dentition is typically done in two stages. In the first stage, an incision is made through the gingiva to expose the underlying bone. An artificial tooth root, usually a threaded dental implant, is placed in the jawbone for integration. The threaded dental implant generally includes a threaded bore to receive a retaining screw holding mating components therein. During the first stage, the gum tissue overlying the implant is sutured and heals as the osseo-integration process continues.
Once the osseo-integration process is complete, a second stage is initiated. Here, the gum tissue is re-opened to expose the end of the threaded dental implant. A healing abutment or a temporary abutment is fastened to the exposed end of the threaded dental implant to allow the gum tissue to heal there around. Preferably, the gum tissue heals such that the aperture that remains generally approximates the size and contour of the aperture that existed around the natural tooth that is being replaced. To accomplish this, the abutment attached to the exposed end of the threaded dental implant has the same general contour as the gingival portion of the natural tooth being replaced. During the typical second stage of dental restoration, the abutment is removed and an impression coping is fitted onto the exposed end of the implant. This allows an impression of the specific region of the patient's mouth to be taken so that an artificial tooth is accurately constructed.
More recently, a single stage dental restoration is also being employed, wherein a healing abutment or a temporary abutment is fixed on the threaded dental implant immediately following the placement of the implant in the jaw bone.
The healing abutment or the temporary abutment is generally screwed to the implant realizing a coupling which can result to be unreliable and not steady, particularly when the coupling part of the abutment with a titanium dental implant is made of ceramics or plastic material. Similar drawbacks also apply to a non-provisional abutment.
A coupling between a threaded titanium dental implant and a permanent ceramic abutment including an intermediate element therebetween made of titanium is known from EP 1 269 932 A1. The object of EP 1 269 932 A1 is the provision of an anti-rotation lock between dental implant and the intermediate element, such that the known arrangement may sustain larger forces, which act with different eccentricity on the dental prosthesis carried by the permanent abutment. To this end, anti-rotation means are provided on the intermediate element and on the dental implant, thus ensuring a positive lock between the intermediate element and the dental implant when a connection screw is tightened at one end into a specially designed hole provided axially inside the dental implant, while at its other end the screw head retains the ceramic abutment against the intermediate element.
The implant system disclosed by the prior art of EP 1 269 932 A1 leaves unsolved several technical problems and suffers some drawbacks.
In fact, in general, the above prior art implant system does not allow to provide for a satisfactory coupling between the intermediate element and the abutment. Also the force distribution and force transmission from the abutment to the implant suffers drawbacks.
In addition, the positioning of the intermediate element with respect to the abutment and the dental implant is difficult.
Further, a separate intermediate element is difficult to manufacture and entails additional costs, which are not desirable, in particular in respect to healing abutments or temporary abutments.
Moreover, in some cases, when for instance the implant is inserted into a biologically aggressive environment, a further problem may arise, as the known intermediate element has a surface which faces outward and the intermediate element outside surface is specially designed in order to be in contact with the gum tissue or with the gum-tissue/jawbone interface. Due to the design of the intermediate element, the prior art implant system presents two interfaces facing outward to the natural tissues: the first interface is at the abutment-intermediate element interface, the second interface is the intermediate element-dental implant interface. It is known to the experts in the art, that the implant systems are normally inserted into a biologically aggressive environment, and so implant interfaces are a point of possible microbiological attack, being rather impossible to precisely realize the joint between the various elements.